2. That of Descartes. We have the idea of an infinite and perfect Being. This idea cannot be derived from imperfect and finite things. There must therefore be an infinite and perfect Being who is its cause.
But we reply that this argument confounds the idea of the infinite with an infinite idea. Man's idea of the infinite is not infinite but finite, and from a finite effect we cannot argue an infinite cause.
This form of the Ontological Argument, while it is a priori, as based upon a necessary idea of the human mind, is, unlike the other forms of the same argument, a posteriori, as arguing from this idea, as an effect, to the existence of a Being who is its cause. A posteriori argument = from that which is later to that which is earlier, that is, from effect to cause. The Cosmological, Teleological, and Anthropological Arguments are arguments a posteriori. Of this sort is the argument of Descartes; see Descartes, Meditation 3: “Hæc idea quæ in nobis est requirit Deum pro causa; Deusque proinde existit.” The idea in men's minds is the impression of the workman's name stamped indelibly on his work—the shadow cast upon the human soul by that unseen One of whose being and presence it dimly informs us. Blunt, Dict. of Theol., 739; Saisset, Pantheism, 1:54—“Descartes sets out from a fact of consciousness, while Anselm sets out from an abstract conception”; “Descartes's argument might be considered a branch of the Anthropological or Moral Argument, but for the fact that this last proceeds from man's constitution rather than from his abstract ideas.” See Bib. Sac., 1849:637.
3. That of Anselm. We have the idea of an absolutely perfect Being. But existence is an attribute of perfection. An absolutely perfect Being must therefore exist.
But we reply that this argument confounds ideal existence with real existence. Our ideas are not the measure of external reality.
Anselm, Proslogion, 2—“Id, quo majus cogitari nequit, non potest esse in intellectu solo.” See translation of the Proslogion, in Bib. Sac., 1851:529, 699; Kant, Critique, 368. The arguments of Descartes and Anselm, with Kant's reply, are given in their original form by Harris, in Journ. Spec. Philos., 15:420-428. The major premise here is not that all perfect ideas imply the existence of the object which they represent, for then, as Kant objects, I might argue from my perfect idea of a $100 bill that I actually possessed the same, which would be far from the fact. So I have a perfect idea of a perfectly evil being, of a centaur, of nothing,—but it does not follow that the evil being, that the centaur, that nothing, exists. The argument is rather from the idea of absolute and perfect Being—of “that, no greater than which can be conceived.” There can be but one such being, and there can be but one such idea.
Yet, even thus understood, we cannot argue from the idea to the actual existence of such a being. Case, Physical Realism, 173—“God is not an idea, and consequently cannot be inferred from mere ideas.” Bowne, Philos. Theism, 43—The Ontological Argument “only points out that the idea of the perfect must include the idea of existence; but there is nothing to show that the self-consistent idea represents an objective reality.”I can imagine the Sea-serpent, the Jinn of the Thousand and One Nights, “The Anthropophagi, and men whose heads Do grow beneath their shoulders.” The winged horse of Uhland possessed every possible virtue, and only one fault,—it was dead. If every perfect idea implied the reality of its object, there might be horses with ten legs, and trees with roots in the air.
“Anselm's argument implies,” says Fisher, in Journ. Christ. Philos., Jan. 1883:114, “that existence in re is a constituent of the concept. It would conclude the existence of a being from the definition of a word. This inference is justified only on the basis of philosophical realism.” Dove, Logic of the Christ. Faith, 141—“The Ontological Argument is the algebraic formula of the universe, which leads to a valid conclusion with regard to real existence, only when we fill it in with objects with which we become acquainted in the arguments a posteriori.” See also Shedd, Hist. Doct., 1:331, Dogm. Theol., 1:221-241, and in Presb. Rev., April, 1884:212-227 (favoring the argument); Fisher, Essays, 574; Thompson, Christian Theism, 171; H. B. Smith, Introd. to Christ. Theol., 122; Pfleiderer, Die Religion, 1:181-187; Studien und Kritiken, 1875:611-655.
Dorner, in his Glaubenslehre, 1:197, gives us the best statement of the Ontological Argument: “Reason thinks of God as existing. Reason would not be reason, if it did not think of God as existing. Reason only is, upon the assumption that God is.” But this is evidently not argument, but only vivid statement of the necessary assumption of the existence of an absolute Reason which conditions and gives validity to ours.
Although this last must be considered the most perfect form of the Ontological Argument, it is evident that it conducts us only to an ideal conclusion, not to real existence. In common with the two preceding forms of the argument, moreover, it tacitly assumes, as already existing in the human mind, that very knowledge of God's existence which it would derive from logical demonstration. It has value, therefore, simply as showing what God must be, if he exists at all.